Cable data systems are used to allow cable TV subscribers use the Hybrid-Fiber-Coax network as a communication link between their home networks and the Internet. As a result, computer information (Internet Protocol packets) can be transmitted across the Hybrid-Fiber-Coax network between home computers and the Internet. The Data Over Cable Service Interface Specification (“DOCSIS”)—defined by CableLabs™—specifies the set of protocols that must be used to effect a data transfer across the Hybrid-Fiber-Coax network (“HFC”). Two fundamental pieces of equipment facilitate this data transfer: a cable modem (“CM”) which is positioned in the subscriber's home, and a Cable Modem Termination System (“CMTS”) which is positioned in the head end of the cable TV company.
In addition to data traffic, subscribers are more and more obtaining telephony voice services over networks other than the traditional public switched telephone network (“PSTN”). A multiple services operator (“MSO”) may provide such telephony services, in addition to data over cable service via DOCSIS. For example, CableLabs has established the PacketCable™ standard for providing telephony services over cable. A subscriber typically has a device that includes a DOCSIS cable modem for transmitting and receiving data and a media terminal adaptor (“MTA”), or embedded MTA (“eMTA”) for processing voice traffic for transmission and reception over cable.
To send and receive telephony/voice calls using a cable modem, a user may couple a traditional telephony device to a subscriber line interface (“SLIC”) jack, typically an RJ-11 jack. The operation of the telephony device coupled in this fashion should be transparent to the user, i.e., it operates as if it were plugged into a traditional RJ-11 telephone jack coupled to the PSTN.
In addition to a standard telephony device being coupled to a cable modem/EMTA, a user device that is designed to send and receive internet protocol (“IP”) packets may be used. Session Initiation Protocol (“SIP”) may be used for call setup signaling. SIP is a protocol that includes logical devices for processing call set up packets, and is designed to operate peer-to-peer with other SIP-based devices. Certain SIP-based devices or logical blocks facilitate traditional PSTN service features, such as, for example, legal interception of calls, emergency calls, such as 911 in United States. Further background information relative to SIP may be found in IETF RFC 3261, entitled “SIP: Session Initiation Protocol,” which may be found at www.ietf.org and is incorporated by reference herein in its entirety.
Subscriber expectations include PSTN-equivalent primary line service that includes high availability and access to E911/911 services. Availability for telephone service from the PSTN is generally specified as five-nines and equates to 99.999% uptime. Five-nines availability corresponds to a down time on the order of five minutes per year. This amounts to a requirement that a PSTN telephone is always available for making emergency calls.
Telephony modems that reset for unknown reasons are at risk of not meeting the five-nines availability requirement. Each telephony modem reset can take up to 1½ minutes to recover. At this rate, it only takes a few resets to eat up the five minutes per year downtime. If telephony modems are resetting, then system operators need to know the reasons for the resets in order to make corrections, whether in the devices or in the network conditions. Thus, there is a need for a method of collecting the reset data and making it available to system operators.